Compound Parabolic Concentrator Design for Equatorial Africa
Compound Parabolic Concentrators (CPC) design uses interposed optical devices (such as parabolic trough, parabolic dish, linear Fresnel reflectors, etc) between the source of radiation (Sun in this case) and the energy absorbing surface (solar cell). The CPCs can be either symmetric or asymmetric. Nigeria lies between latitude 4°N to 14°N and Longitude 2°E to 15°E while Abuja where this project will be experimented lies between 9.176°N and longitude 7.181°E. Nigeria is close to the Equator and has lower altitude unlike the United Kingdom that has higher altitudes to the sun. Asymmetric CPC is best applicable in countries with higher altitudes like the UK while symmetric CPC is best applicable in countries having lower altitudes. There are majorly two motivations of using concentration in solar collectors The first is to improve performance such as effective geometric concentration ratio, concentration ratio and optical efficiency the second motivation is reducing the cost by the optimization of the concentrator profile such as the solar incident angle and height of the concentrator. There are two related approaches that are possible for CPC design. The first one is the use of non-imaging concentrators and the second one is the use of imaging concentrators. The focus of the present work is to design and develop solar concentrator that is stationary and able to harness solar energy in the maximum. It is symmetric 3D CPC with a concentration ratio of 3X. It is a non-imaging concentrator to achieve high energy generation for stand-alone or mini-grids for built environment. The approximate factors that are to be optimized to increase the radiation flux on the energy absorbing surfaces are – i) the ray distribution on the concentrator, ii) ray focusing on the solar cell, and iii) the CPC design to reduce ray leakage or energy loss. This is approached by the method of using coordinate systems, solid works, solid edge and optics work software. The calculated acceptance apertures and CPC heights for the chosen acceptance half angles obtained after Intensive modelling indicate that the height of CPC could be truncated without losing the required concentration ratio of 3X thereby reducing the material cost. The CPC system designed in the present study is expected to have low cost, high efficiency with reliable improved performance to generate power that will contribute to addressing power demand in the equatorial countries like Nigeria and Africa at large.
compound parabolic concentrator; concentration ratio; concentrator; entrance aperture; absorber length; acceptance angle; height of CPC
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